When excavating a site for construction, calculable dangers exist to workers that are dependent on the design and construction of the shield system. Regulations promulgated by the United States Department of Labor, Occupational Safety & Health Administration (herein "OSHA") under 29 C.F.R. .sctn.1926.650 defines a "shield system" as:
a structure that is able to withstand the forces imposed on it by a cave-in and thereby protect employees within the structure. Shields can be permanent structures or can be designed to be portable and moved along as work progresses. Additionally, shields can be either premanufactured or job-built in accordance with .sctn.2936.653(c) or (c)(4).
In one type of excavation procedure, typically used to install and replace petroleum tanks, a trench is dug around the perimeter of the excavation site and steel H-beams are placed into the trench. The beams are also known as "wales" which are placed parallel to the excavation face and whose sides bear against the vertical members of a shoring system or the earth. The wales are welded together to form a substantially rigid rectangle around the perimeter. Corrugated shield panels, also known as "uprights," are the vertical members of a trench shoring system and are placed in contact with the earth and usually positioned so that individual members do not contact each other. However, uprights may be in contact with or interconnected to each other, which is known as "sheeting." The uprights are placed on the outside periphery of the substantially rigid rectangle and are vertically driven into the ground. A support means is attached to each corner of the substantially rigid rectangle and ground beneath the wales is subsequently excavated thereby leaving the wales suspended at each comer of the substantially rigid rectangle by the support means. The support means typically comprises a chain link or heavy cable. Once work is completed within the excavation site, the wales must be welded apart and removed from the construction area.
However, repeated welding to join and cut the wales may cause structural faults in the wales and calculating the force that a weld can resist is difficult. Welding introduces safety hazards inherent in the procedure which are further compounded when working around legacy petroleum tanks. Lastly, welding is a specialized skill that requires expendable resources, equipment, and time.
Consequently, there is a need in the art for an apparatus for excavations that insures the strength of the shield system to protect workers against cave-ins.
There is a further need in the art for an apparatus to interconnect existing wales in a shield system without the need for welding.
There is a further need in the art for an apparatus that alleviates the need to weld the wales together in the shield system described above.
There is a further need in the art for an apparatus that requires a low amount of skill and training to operate safely and efficiently.
There is a further need in the art for an apparatus that does not degrade the structural integrity of the wales after repeated use.
There is a further need in the art for an apparatus that may be reused without diminution of effectiveness in excavations.
However, in view of the prior art in at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified needs could be fulfilled.